In recent years, a transmission/reception system in a wireless communication system such as a mobile phone actively uses wider bandwidth and multiple bandwidths to meet various wireless standards such as GSM, GPS, and WCDMA. Currently, many applications appear which use such various wireless communication systems.
It is expected that a trend in which a plurality of wireless standards are supported by one wireless terminal will be more accelerated. However, in a wireless terminal that supports a plurality of wireless standards, there is a risk that a transmission/reception signal of one wireless standard may be an in-band or out-of-band interference wave of the other wireless standards. Therefore, the effect of insensitivity, the intermodulation distortion, and the secondary distortion due to the in-band or out-of-band interference wave degrade the S/N ratio of a desired signal. Therefore, it is very important to design a wireless system and a circuit by sufficiently considering the interference waves of other systems.
Many SAW filters having a sharp Q value and duplexers have been used to solve the above problem. However, that approach increases cost, therefore, in these few years, techniques for reducing external components as much as possible have been developed. A technique for integrating external components into a chip as on-chip components in order to further reduce cost is becoming a mainstream technique. However, when external components are integrated into a chip as on-chip components, the power consumption increases. It is required to reduce the power consumption, in particular, for applications such as a mobile phone and a wireless game controller, which are desired to be able to be used for a long time.